1. Field of the Invention
The present invention relates to an admission control method in an Internet differentiated service network, and more particularly to an admission control method in an Internet differentiated service network, which performs an admission control function by integratedly applying a bandwidth broker function, a movable boundary function, and a measurement based admission control function to an Internet differentiated service network.
2. Description of the Prior Art
In recent times, following the current trend of rapidly developing data transmission technology, Internet networks using an xDSL or a metro Ethernet, etc. are increasingly developed to have a broadband and a variety of Internet multimedia contents are also increasingly developed. So, a variety of application services requiring QoS (Quality Of Service) guarantee, for example, an Internet broadcasting service, a VoIP (Voice over IP) service, and a VPN (Virtual Private Network) service, are newly introduced to the market. As a result, QoS guarantee technology in an Internet network has become a popular research subject to provide Internet service users with various services.
Therefore, QoS guarantee technologies for satisfying bandwidth requirements, transmission reliability, and real-time characteristics in order to support service applications having a variety of requirements should be proposed in an Internet network.
There are various kinds of QoS guarantee technologies providable in an IP (Internet Protocol) network, for example, an admission control method, a congestion control method, and traffic shaping/metering/marking/scheduling methods, etc. The most important method among the aforementioned methods associated with the QoS guarantee technologies is the admission control method. The purpose of the admission control method is to allocate network resources in such a way that reliable paths for ensuring packet loss probability or delay requirement requested by a user can be provided in such a network.
There have been widely studied two kinds of conventional arts related to such an admission control method, that is, a parameter based admission control method and a measurement based admission control method. In more detail, the parameter based admission control method performs an admission control function with reference to a plurality of parameters, i.e., a peak rate, a mean rate, and a delay variation, etc., which are proposed by a signaling protocol in the case where a user establishes a connection setup request in a telephone network or packet network.
The measurement based admission control method performs an admission control function by measuring the used amount of traffic on a current link. There are two kinds of such a measurement based admission control method, that is, a data packet measurement method and a probing packet measurement method. The data packet measurement measures data traffic being currently transmitted, predicts the future traffic based on the measured data traffic, and finally performs an admission control function. The probing packet measurement method determines whether there is a sufficient bandwidth in each node on a path by previously transferring a plurality of probing packets corresponding to the amount of traffic requested by a connection setup procedure to a network, and then performs an admission control function.
In addition, another admission control function of a centralized management method using a bandwidth broker has also been used in a conventional art. In this case, a bandwidth broker determines whether a service requested by a user is accepted, and performs an intra-network resource allocation. Presently, a static provisioning method is adapted to perform network resource management using a bandwidth broker. The static provisioning method allocates such network resources to a specified routing path predetermined by a SLA (Service Level Agreement) in an off-line state at intervals of a predetermined time (e.g., day, week, or month), and determines admission or denial on the basis of a new connection request entered by a user.
On the other hand, a dynamic provisioning method allows the bandwidth broker to periodically receive network status information from each node contained in a network, and the received network status information is reflected in a resource allocation procedure. As a result, the dynamic provisioning method dynamically varies a resource allocation procedure according to such a network status or routing variance, and finally performs an admission control function on the basis of a new connection request entered by a user.
The parameter based admission control method among the aforementioned conventional admission control methods has a scalability problem when it is applied to an Internet network, because parameter and status information related to each connection requested from each edge node of intra-network ingresses should be managed in all the nodes. Therefore, the parameter based admission control method has limitations in that it is not applied to a large-sized Internet-core network. Further, the measurement based admission control method has difficulty in estimating an input traffic on the basis of a mean arrival rate of a steady state related to the input traffic, thereby causing an inaccurate admission control operation.
In the meantime, the above static provisioning method using a bandwidth broker causes data congestion because it is not adapted to a network status such as dynamically variable Internet traffic or routing, and does not effectively use network resources because changes in network resource allocation are established at intervals of a predetermined time. A currently investigated dynamic provisioning method requires complicated bandwidth management information to enable a bandwidth broker to manage even bandwidth of an intra-network link level, and should periodically receive an intra-network congestion state or the used amount of a link's bandwidth from each node, thereby correcting related information.
One representative example related to such an admission control method has been described in a PCT application No. PCT/US99/27380, entitled “PROVIDING ADMISSION CONTROL AND NETWORK QUALITY OF SERVICE WITH A DISTRIBUTED BANDWIDTH BROKER”, which is incorporated herein by reference. This PCT application performs an admission control function using local bandwidth information through the use of a local bandwidth broker distributed to each node for satisfying user's QoS requirements in an Internet network such that each node contained in a network performs an admission control function using a control message. However, the above PCT application has disadvantages in that it should use a control message for bandwidth reservation as in a signaling method of a conventional packet switching system and should store status and session information for the bandwidth reservation.
A measurement based admission control mechanism based on an end-to-end probing packet and a performance analysis thereof have been proposed by Viktoria Elek, who has published a research paper entitled “CONTROL BASED ON END-TO-END MEASUREMENT” in an IEEE INFORCOM2000 Proceeding pp. 623˜630 on April 2000. The measurement based admission control mechanism transmits probing packets equal to the amount of bandwidths to be transmitted by a transmitter over the Internet to a receiver during a probing period, and then receives information related to such a probing packet transmission. In this case, if the reception information has a better QoS than a target QoS, the mechanism establishes connection setup admission. However, this mechanism also has a disadvantage in that an additional Queue should be contained in a core network to discriminate between a probing packet and a data packet and a priority queue management method should be used.
Further, an admission control method using a dynamic bandwidth allocation method based on a quota in a bandwidth broker has been proposed by Zhi-Li Zhang, who has published a research paper entitled “ON SCALABLE DESIGN OF BANDWIDTH BROKERS” in an IEICE Trans. Commun., Vol. E84-B No.8, pp. 2011˜2025 on August 2000. This admission control method manages a QoS status with a path level and a link level through the use of a bandwidth broker, and initially allocates bandwidths to a path in quota units to perform an admission control function. Thereafter, after using all of the allocated quotas, the admission control method determines whether a new quota is allocatable to all the links on a path. If it is determined that a new quota is allocatable to them, the admission control method establishes allocation of such a new quota such that it performs an admission control function. However, the above admission control method has a problem related to a value of the quota unit, and should investigate bandwidths of all the links on a path to perform a new quota allocation when quotas allocated to the path are all used.